The present invention relates to a cigarette filter, method and apparatus for making the same.
It is already known to connect a filter to a cigarette having means for introducing air therein in order to decrease the amount of smoke in inhaled content. Some of such examples are seen in the Japanese patent publication before examination No. 55-141184, 57-122784 and 57-132873.
In the prior art mentioned above, such introduced air penetrates along the periphery of the filter and is inhaled by a smoker as if it encloses a flow of thick smoke flowing through the central portion of the filter. Therefore, the amount of smoke inhaled by the smoker is diminished or diluted, thus producing light taste to the smoker's satisfaction.
In the Japanese patent publication before examination No. 55-141184, it is disclosed that both filter and plug paper are formed of grooves on their peripheries by heating in advance and when said filter is integrated with a cigarette by tip paper, air passages are defined by said tip paper and grooves. In this case, since the grooves are molded by heating, high speed production is difficult to attain. Furthermore, when heating is applied in the molding process, the grooved area is inclined to shrink diminishing the cross sectional dimension of the filter where smoke flows through and creating non-uniformity in the cross sectional dimensions of the grooves. As a result, the amount of introduced air penetrating along the periphery of the filter becomes uneven.
On the other hand, in the Japanese patent publication before examination No. 57-122784, plug paper is applied to the filter by a conventional method, and then the filter and cigarette are integrated by tip paper having a plurality of knobs formed in advance for forming channels extending in the axial direction so that air passages are defined by said plug paper and channels. In this prior art, it is extremely difficult to speed up the work to connect the filter to the cigarette by tip paper.
The present invention is accomplished in order to overcome the above mentioned disadvantages of the prior art.